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BI 212 > Chapter 20 EXAM @ > Flashcards

Chapter 20 EXAM @ Flashcards

1
Q

Define the cardiac cycle.

A

Period of time fr start of 1 heart beat to the start of next

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2
Q

Cardiac muscle tissue contracts on its own without neural or hormonal stimulation b/c of a phenomenon known as what?

A

Automaticity

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3
Q

What are the 3 components of the cardiac conducting system?

A

Sinoatrial Node
Atrioventricular node
Conducting cells

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4
Q

The SA node is located where?

A

Posterior wall of the R atrium nr entrance of the superior venacava

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5
Q

What is the location of the atrioventricular node?

A

Within the fl of the R atrium nr the opening of the coronary sinus

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6
Q

What pathways does a contractile stimulus follow to atrial muscle cells as an electrical impulse travels fr the SA node to the AV?

A

Internodal pathways

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7
Q

Which conducting cells are located in the ventricles?

A

AV bundle (bundle of his)
Bundle branches
Purkinje fibers

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8
Q

The gradual depolarization of the conducting cells of the SA node and the AV node is known as ___.

A

Prepotential

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9
Q

What causes pre potential of cardiac cells?

A

Slow influx of Na+ w/o a compensating outflow of K+

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10
Q

The ___ node generates action potentials at a rate of 80-100 per minute

A

SA

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11
Q

The AV node generates action potentials at what rate?

A

40-60/min

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12
Q

The SA node contains ___ ___ which set the heart rate.

A

Pacemaker cells

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13
Q

What connects the SA node to the AV node?

A

Internodal pathways

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14
Q

The connection between the AV node and the ___ ___ (aka ___ of ___), is normally the only elec connection between the atria and the ventricles.

A

AV Bundle

Bundle of his

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15
Q

Once an impulse enters the AV bundle, it travels to the interventricular septum and enters what part of the conduction sys?

A

Right and left bundle branches

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16
Q

What is an ectopic pacemaker?

A

Cells outside the conduction sys that set the HR that disrupt the the timing of the ventricular contraction

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17
Q

Which wave on the EKG represents the atrial depolarization?

A

P wave

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18
Q

The smaller ___ wave indicates ventricular depolarization.

A

T

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19
Q

The ___ interval extends fr the start of atrial depolarization to the start of the QRS complex

A

P-R

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20
Q

Extension of the P-R interval to longer than ____ can indicate damage to the conducting pathways or the AV node.

A

200 msec

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21
Q

The Q-T interval indicates what?

A

Time required for the ventricles to undergo a single cycle of depolarization and repolarization

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22
Q

What are some of the causes of long QT syndrome?

A 
Electrolyte disturbances
Meds
Conduction probs
Coronary ischemia 
Myocardial damage
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23
Q

An ____ is an irregularity in the normal rhythm or force of the heartbeat.

A

Arrhythmia

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24
Q

Serious arrhythmias may indicate what issues?

A

Damage to myocardium
Injuries to pacemakers or conduction pathways
Exposure to drugs
Abnormalities in electrolyte composition of
extracellular fluids

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25
Q

What is the resting potential of a ventricular contractile cell?

A

-90mV

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26
Q

An action potential begins when the membrane of ventricular muscle reaches threshold at approx ____ mV.

A

-75 mV

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27
Q

What are the 3 steps in an action potential?

A
  1. Rapid Depolarization
  2. The Plateau
  3. Repolarization
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28
Q

Fast sodium channels open during the rapid depolarization phase of an action potential. They are called fast channels b/c . . . .

A

They open quickly & remain open only for a few milliseconds

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29
Q

At what point in the action potential of a cardiac cell do sodium channels close?

A

As transmembrane potential reaches +30mV

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30
Q

Voltage gated Ca+ channels are known as slow Ca+ channels. Why?

A

B/c they open slowly & remain open for for a relatively long period

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31
Q

What causes the rapid depolarization phase of an action potential?

A

Na+ entry

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32
Q

How long does the rapid depolarization phase of an action potential last?

A

3-5 msec

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33
Q

What is the last thing that happens during the depolarization phase of the action potential?

A

Closure of voltage gated fast sodium channels

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34
Q

The plateau phase of the action potential begins with what?

A

Ca2+ entry

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35
Q

The plateau phase of the action potential lasts how long?

A

-175 msec

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36
Q

The plateau phase of the action potential ends with the closure of ___ ___ ___.

A

Slow calcium channels

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37
Q

What causes the repolarization phase of the action potential to start?

A

Loss of K+

38
Q

What is the duration of the repolarization phase of an action potential?

A

75 msec

39
Q

The repolarization phase of the action potential ends with what?

A

Closure of slow K channels

40
Q

The period when a membrane will not respond to another stimulus for sometime after and action potential begins is know as what?

A

Refractory Period

41
Q

What is the approx length of the refractory period in ventricular muscle?

A

200 msec

42
Q

Define cardiac cycle.

A

The period between the start of one heart beat & the beginning of the next

43
Q

What are the 2 phases of the cardiac?

A

Systole and Diastole

44
Q

The phase in the cardiac cycle when a chamber contracts and pushes blood is known as what?

A

Systole

45
Q

The phase in the cardiac cycle when the muscle relaxes and the chambers fill is known as ___.

A

Diastole

46
Q

The brief period when all heart valves are closed, volumes in the ventricles do not change and ventricular pressures are rising is known as ___ ___.

A

Isovolumetric Contraction

47
Q

What IDs the beginning point of ventricular ejection?

A

When pressure in ventricles exceeds that in arterial trunks, semilunar valves open and blood flows

48
Q

During ventricular ejection each ventricle ejects 70-80 mL of blood. This is known as what?

A

Stroke volume

49
Q

The amt of blood remaining in the ventricle when the semilunar valve closes is known as what?

A

End-systolic volume

50
Q

The period when heart valves are closed, ventricular myocardium is relaxing and ventricular pressures are still higher than atrial pressures is known as what?

A

Isovolumetric relaxation

51
Q

What happens to ventricular pressure during isovolumetric relaxation?

A

Ventricular pressure drops rapidly

52
Q

Heart sound S1 marks what in the cardiac cycle?

A

Start of ventricular contraction when the AV valves close

53
Q

When does the heart sound S2 occur?

A

At beginning of ventricular filling when semilunar valves close

54
Q

What is occurring during heart sound S3?

A

Blood is flowing into the ventricles

55
Q

What is occurring during heart sound S4?

A

Atrial contraction

56
Q

What causes a heart murmur?

A

Probs w/papillary muscles or chordae tendineae causing heart valves to not close properly causing AV valve regurgitation

57
Q

What is the term used to refer to the movements and forces generated during cardiac contractions?

A

Cardiodynamics

58
Q

The amt of blood left in the ventricles at the end of ventricular diastole is called what?

A

End Diastolic Volume

59
Q

The amt of blood left in the ventricles at the end of ventricular systole is called ___ -___ volume.

A

End-systolic

60
Q

What is stroke volume?

A

Amt of blood pumped out of each ventricle during a single beat

61
Q

What is the equation for Stroke Volume?

A

SV = End diastolic vol - End Systolic vol

62
Q

The percentage of the End diastolic col represented by the Stroke Vol is called ___ ___.

A

Ejection Fraction

63
Q

Define cardiac output.

A

Amt of blood pumped out of the L ventricle in one minute

64
Q

What equation can we use to determine cardiac output?

A

CO = HR x SV

65
Q

What are 2 factors affecting HR?

A

Autonomic Innervation

Hormones

66
Q

What are 2 factors affecting stroke vol?

A

End diastolic vol

End systolic vol

67
Q

The ANS and PNS innervate the heart by means of the nerve network known as the ___ ___.

A

Cardiac plexus

68
Q

What is the location of the autonomic HQ for cardiac control?

A

Cardiac centers of the medulla oblongata

69
Q

The ____ center controls sympathetic neurons that increase HR.

A

Cardioacceleratory

70
Q

The ____ center controls parasympathetic neurons that slow HR.

A

Cardioinhibitory

71
Q

Where do the cardioacceleratory and cardioinhibitory centers receive their info from?

A

Reflex pathways
Higher centers
PNS & SNS ctrs in Hypothalamus

72
Q

Cardiac centers monitor baroreceptors and chemoreceptors innervated by what 2 nerves?

A

Glossopharyngeal (CN IX)

Vagus (CN X)

73
Q

Cardiac centers respond to changes in ___ ___ reported by baroreceptors and to what 2 things from chemoreceptors?

A

Blood Pressure

Changes in arterial concentrations of dissolved O2 and CO2

74
Q

What are 2 ways to increase HR through ANS innervation?

A

Decrease PNS activity

Increase SNS activity

75
Q

How do SNS and PNS alter HR?

A

By changing ionic permeabilities of cells in the conducting sys.

76
Q

Adjustments in HR in response to increases in venous return are caused by what reflex?

A

Arterial reflex of Bainbridge principle

77
Q

What is the term given to the amt of blood returning to the heart by the veins?

A

Venous return

78
Q

___, ___ and thyroid hormone increase HR by their effect on the SA node.

A

Epi

Norepi

79
Q

____ ___ is the duration of ventricular diastole and is dependent upon what?

A

Filling time

HR

80
Q

The degree of stretching in ventricular muscle cells during ventricular diastole is called ____.

A

Preload

81
Q

Preload is directly proportional to what?

A

EDV

82
Q

The idea that increasing EDV results in a corresponding increase in stroke vol is know as ___-___ principle.

A

Frank-Starling

83
Q

___is the amt of force produced during a contraction at a given preload.

A

Contractility

84
Q

Inotropy is a term that is related to what with regards to the heart?

A

Force of contraction (contractility)

85
Q

SNS stimulation has a ____ inotropic effect where as PNS stimulation has a ____ inotropic effect.

A

Positive

Negative

86
Q

The ___ is the amount of tension that the contracting ventricle must produce to force open the semilunar valve and eject blood.

A

Afterload

87
Q

As afterload ____ stroke volume ____.

A

Increases

Decreases

88
Q

An increase in venous return stretches nodal cells and produces what effect?

A

Increases HR

89
Q

Stroke vol is the difference between what and what?

A

EDV and ESV

90
Q

What 3 factors effect ESV?

A

Preload
Degree of contractility
Afterload

91
Q

The difference between resting and maximal cardiac output is known as ___ ___.

A

Cardiac reserve

BI 212 (7 decks)

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